Round head bolts, also known as button head bolts, are characterized by their smooth, rounded heads, offering an aesthetically pleasing appearance along with functional advantages. The rounded profile reduces the risk of snagging and provides a flush finish when installed, making them suitable for applications where surface smoothness and visual appeal are important, such as in furniture, electronics, and decorative fixtures.
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Standard
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Country/Region
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Description
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ISO 7380
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International
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Specifies dimensions and requirements for round head bolts with metric threads
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DIN 603
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Germany
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Defines the characteristics of round head square neck carriage bolts
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ASME B18.3
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USA
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Covers socket head cap screws, including round head variants in unified series
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GB/T 818 - 2000
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China
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Details the specifications for round head slotted screws
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JIS B 1111
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Japan
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Japanese standard for round head bolts with specific dimensional tolerances
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Grade
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Material
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Tensile Strength (MPa)
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Application Scenarios
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4.8
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Low-carbon steel (e.g., Q235)
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400/320
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General assembly in non-critical household items
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8.8
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Medium-carbon steel (e.g., 45# steel)
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800/640
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Automotive interior components, general machinery
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10.9
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Alloy steel (e.g., 35CrMo)
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1000/900
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High-stress applications in industrial equipment
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A2-70 (Stainless Steel)
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304 stainless steel
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700
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Corrosion-resistant applications like kitchen appliances
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A4-80 (Stainless Steel)
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316 stainless steel
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800
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Marine environments and chemical processing equipment
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Aluminum Alloy
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6061 aluminum
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276
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Lightweight structures in aerospace and electronics
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Treatment Method
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Abbreviation
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Description
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Zinc Plating
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Zn
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Basic rust protection, available in various colors for decorative purposes
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Electroplating
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-
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Offers a thin, uniform coating; enhances appearance and provides light corrosion resistance
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Anodizing (for Aluminum)
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-
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Increases surface hardness and corrosion resistance of aluminum bolts, available in multiple colors
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Passivation (for Stainless Steel)
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-
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Improves the corrosion resistance of stainless steel by forming a protective oxide layer
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Powder Coating
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-
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Provides a durable, decorative finish with good abrasion and chemical resistance
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Black Oxide Coating
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Black
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Creates a black, non-reflective surface with moderate rust resistance, suitable for internal components
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